A double-layer tablet is a double-phase medicine-release system having a double-layer structure, which not only can achieve the ideal pharmacokinetic behavior by combining two medicines together or combining identical medicine in different release modes together, but improve the stability of the medicines having incompatibility and give the special functions to the tablet.
In preparation of the double-layer tablet, to ensure the medicine of double-layer tablet has the stable structure during the shelf life is the most demanding and practical technology in pharmaceuticals industry.
The double-layer tablet in the prior art includes two layers of tablets which are adhered to each and the preparation method thereof is to press the two layers of tablets one by one usually, for example, mix the medicinal active ingredients and the pharmaceutical excipients of one layer of the double-layer tablet and press the mixture into one layer of tablet; then prepare the double-layer after pressing this tablet with the medicinal active ingredients and the pharmaceutical excipients of the other layer of tablet together.
The double-layer tablet of the prior art is featured with poor physical stability, easy breaking and separation of the two layers; and the preparation may be cracked, etc. during transportation and storage as a result of difference of dilatation coefficients among the different pharmaceutical excipients because different pharmaceutical excipients are applied to the two layers of tablets usually.
Therefore, it is necessary to improve the physical stability of the double-layer tablet and ensure integrity of the preparation during transportation and storage.